Here are some starting places-- I like browsing around the recommendations at Amazon. The only one of these that I've bought is "Words on the Vine", but DS liked it some time back. There are lots of similar resources out now.

Greek and Latin Roots
Red Hot Root Words
Vocabulary Packets: Greek & Latin Roots
Words on the Vine

Some etymology resources that might spark an interest:

Barnhart Concise Dictionary of Etymology, http://www.amazon.com/gp/product/0062700847 (also see http://www.amazon.com/dp/0550142304)
Word Histories and Mysteries: From Abracadabra to Zeus, http://www.amazon.com/dp/B005Q5TEWO
Word Origins, http://www.amazon.com/Word-Origins-T.../dp/0517265745
The Oxford Dictionary of English Etymology, http://www.amazon.com/dp/0198611129
Origins: A Short Etymological Dictionary of Modern English, http://www.amazon.com/dp/0415050774
The Secret Life of Words: How English Became English, http://www.amazon.com/dp/B004KAB5AU

Striving to increase my rate of flow, and fight forum gloopiness. sick